New approach for estimating the cooling capacity of the absorption and compression chillers in a trigeneration system

This paper presents a multi-objective optimization model for estimating the cooling capacity of refrigeration in a trigeneration system for both grid on and off operating modes. In trigeneration systems, the cooling demand can be provided by single effect absorption and compression chillers (as the refrigeration system). Genetic Algorithm and LINMAP selection procedure are used for obtaining the final optimum point considering four-E analysis (energy, exergy, economy and emission) with the help of net future worth benefit difference (NFWBD) and global exergy efficiency objective functions. It was found that the NFWBD and exergy efficiency with cooling capacity of 1800 and 5600 kW for absorption and compression chillers, respectively, are 330 × 106$ and 41.9% for grid on mode, while they reduce to 232 × 106$ and 32.7% for grid off mode. Sensitivity analysis in grid on mode shows that the increase in the number of equipment (gas engine and chillers) leads to the decrease in both NFWBD and exergy efficiency, while selecting two similar absorption chillers (with cooling capacity of 900 kW), has payback period of 5.1 years, and provides the maximum NFWBD (321 × 106$) and exergy efficiency (40.02%).